Trench Art Round Lidded Metal Box

I am not super confident about identifying trench art--objects made by soldiers or civilians during wartime, from whatever materials they had at hand--but my guess is that this small lidded box is an example, made of an old shell casing. I really love the surface, with this matte copper colored finish worn away around the edges, and its simplicity; just an honestly made thing.   

2 1/4" in diameter x 1 18" tall.